Accelerated Solvent Extraction for Sample Preparation of Chemical Weapon Degradation Compounds
Bibliographic record
Abstract
EXTENDED ABSTRACT A commercially available accelerated solvent extractor (Dionex ASE 200) was utilized for rapid soil extraction of degradation compounds originating from Schedule 1 Chemical Weapons (CW) materials listed under the Chemical Weapons Convention (CWC). Inert 2030 mesh Ottawa sand (Fisher Scientific) and three types of characterized soils including sandy loam, sandy clayloam, and loam (soil #1, #2, and #3, respectively from : RT Corporation) were spiked with part-per-million (ppm) quantities of various degradation compounds, including, but not limited to, methyl phosphonic acid (MPA) and thiodiglycol (TDG). The degradation compounds extracted from the soils were derivitized with 2,2,2-trifluoroN,N-bis(trimethylsilyl)-acetamide (BSTFA) and analyzed via gas chromatography/mass spectrometry (GC-MS) in order to determine percent recoveries and optimize the efficiency of the extractions. Results of these studies include recovery data and optimized methodology. In general, highest recoveries of the target compounds were achieved with extraction temperatures of 100°C and 150°C. Higher temperatures produced lower recoveries, possibly due to breakdown of the target compounds and interference caused by the extraction of large amounts of extraneous organic compounds. Percent recoveries obtained from soil #2 were poor for all target compounds. Inert sand and soil #1 yielded the highest recoveries for most target compounds. The target compounds originating from mustard agents demonstrated the highest recovery percentage (50-90%) of the target compounds investigated here. In addition, an environmental weathering study of spiked soils was performed to evaluate extraction efficiency following weeks of exposure to atmosphere. As expected, trends observed over time exhibit a decrease in percent recovery as exposure time is increased. However, most target compounds were detected at low concentrations after as long as six weeks of exposure to atmosphere in at least one of three sample replicates. The advantages of accelerated solvent extraction (ASE) over other soil extraction methods include a fullyautomated solvent extraction system, fast solvent extractions achieved in minutes, low volumes of solvent required, and good recoveries of compounds originating from mustard agents. However, the disadvantages of ASE extraction include the initial equipment costs and maintenance, moderate to poor recoveries of many target compounds originating from nerve agents, and poor recoveries of all target compounds achieved from soil #2. Although recoveries were poor for some compounds, detection of the target compounds was achieved following ASE extraction in all soil matrices with the exception of MPA (see Table I).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.013 | 0.005 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".